A switched reluctance motor is more advantageous in simple structure, low cost, high torque density and high efficiency than a general motor. However, the switched reluctance motor has a disadvantage in that vibration noise increases by torque pulsation.
In the switched reluctance motor, both a stator and a rotor include a plurality of poles or teeth. The stator includes coils wound, but the rotor does not include a coil or magnet.
The coils of the facing teeth of the stator are connected in series to each other. When the position of the rotor is detected and the current of each phase is on or off, the rotor is rotated.
FIG. 1 is a cross-sectional view illustrating a conventional switched reluctance motor.
Referring to FIG. 1, the conventional switched reluctance motor includes a stator 10 fixedly installed in a motor housing or frame (not shown), a rotor 20 rotatably inserted into the stator 10, and a rotating shaft 30 pressed in the center portion of the rotor 20.
The stator 10 includes a stator core 11 formed by laminating a plurality of steel sheets, a housing hole 11a formed at the center portion of the stator core 11, a plurality of protruded poles 11b inwardly protruded to the housing hole 11a along the radial direction, and formed at interval from each other at predetermined intervals along the circumferential direction, and coils 12 wound around the protruded poles 11b, for generating electromagnetic force by applied power.
The rotor 20 includes a rotor core 21 formed by laminating a plurality of steel sheets. Here, the plurality of steel sheets each respectively have a shaft hole 21a at their center portions to house the rotating shaft 30, and also have a plurality of outwardly protruded poles 21b on the circumference of the shaft hole 21a along the radial direction.
The conventional switched reluctance motor produces noise by BPF elements generated by the shape of the rotor core 21 in the rotation of the rotor core 21, namely, the BPF elements generated when the protruded poles 11b of the stator core 11 and the protruded poles 21b of the rotor core 21 meet each other in the rotation of the rotor core 21.
To solve the foregoing problem, there has been suggested a structure of reducing the BPF elements generated in the rotation of the rotor core 21, by forming resin formation units 40 by filling synthetic resin in slots 11c formed between the protruded poles 11b of the stator core 11.
However, in this structure, air passages between the rotor core 21 and the stator core 11 are blocked by the resin formation units 40 formed inside the slots 11c. Accordingly, heat generated in the rotation of the rotor core 21 is not sufficiently emitted, thereby overheating the coils 12 and the rotor core 21. As a result, efficiency and performance of the motor are reduced.